...the only hints he gave were that he completely rewrote the software...

I figured as much. I've started writing my own software for this as well. Right now it's a series of blinking LED's in the simulator

Also, I was able to confirm that VCC was 5v. (finally found my multimeter )

I figure that since I have the pinouts and a pretty good idea how the platform is supposed to operate (pull trigger => fire gun), I have a good chance in writing something that works. If you'd like to collaborate on this adventure please send me a private message and I'll give you my email address.

I think we've exhausted the Arduino nature of this topic, so this forum is probably not the best place to proceed.

I think we've exhausted the Arduino nature of this topic, so this forum is probably not the best place to proceed.

That is only possibly true if the processor is an ATtiny20. SPI programmable ATtiny processors (e.g. ATtiny84) are very popular in the Arduino world. They can be programmed easily using any Arduino compatible board. There is even a forum section dedicated to the pursuit... Microcontrollers.

ISP = In System Programming. It's a generic term meaning the processor can be programmed after being installed on a board. Atmel processors have several flavours of ISP: Serial (the most Arduino friendly), Parallel, debugWIRE, etcetera.

One of those ISP flavours is "TPI". As far as I can tell, the ATtiny20 only allows TPI programming. The other flavours are not supported. TPI programming has been rarely if ever discussed here.

The processor is essentially a stripped down ATmega328. The folks here have lots of experience with the 328 so I suspect you can get help here regarding low-level hardware questions. But probably not much help regarding uploading the new software via TPI.

Connect how? to have a good seat for programming it or just for probing like with a multimeter??

BTW I tried rubbing alcohol and it didn't work. The T20 is pretty much etched in I believe. I did also make a mistake in trying nail polish remover/acetone....big noob mistake ha.it got rid of the shiny part of the casing and now you cant even read the atmel or the 20sso. Chip/board still works, just now the only thing (from me) we have for studying is the pics haha. Lessons learned

• It is an SPI programmable processor (like an ATtiny44) • You can get some connections to it • RESET has not been disabled • SPI programming has not been disabled

...you can determine exactly which processor it is by reading the signature bytes. With the exception of the physical connections, making the attempt is very unlikely to damage anything. Just include series resistors; 220 ohms works well.

Good find. I do agree with you on the ATtiny44 branding. You must have had some good lights and a good magnifier or good camera (maybe with macro lens). Your text below T20Ver2 is clearer as well. Instead of 20SSO it looks more like 20SSU. From what I've seen on the Atmel site that number doesn't refer to a specific Package or anything like that, it refers to the ordering code. In the case of the ATTiny44 that ordering code links to one with the package of "SOIC (150mil) 14S1 14". Power supply for this chip is 2.7-5.5V and is 20MHz.

You probably have already seen the information, but at least I feel like i'm contributing lol.

For programming an ATTiny44 checkout this webpage as well http://hlt.media.mit.edu/?p=1695

What do I need to connect? Do I connect the programmer's Vcc (5v), MOSI, Reset, SCK, MISO, and Gnd to the respective pins on the ATTINY44? You mentioned 220 ohm resistors, where whould I put them? I see plenty of examples online how to program a chip in isolation, but I can't find anything about programming a chip that's soldered into a production board. I assumed that's what was meant by In-System Programming, but I can't find any good examples.

The target circuit board is powered via a 9v battery, though Vcc for the ATtiny44 is +5v. The only other noteable part of the board would be the 3055L MOFET which I'm guessing is used to drive the Solenoid.

I would guess that the main draw is the solenoid, so as long as the trigger (which activates the Solenoid) is never fired, I'm pretty sure the draw is under 350mA.